<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- 统计字符串中每个字符的个数？以对象的形式返回 -->
    <script>
         var str = 'abcdacbabcbababcbabcabd'
         var res=str.split('').reduce(function(pre,cur){
            if(cur in pre){
                pre[cur]+=1
            }else{
                pre[cur]=1
            }
            return pre
        },{})
        console.log(res);
        
         
    </script>
</body>
</html>